Air Toxics Data Analysis - US EPA · Air Toxics Data Analysis Plan for 2006-2007 National...

Air Toxics Data AnalysisPlan for 2006-2007 National Assessment

National Monitoring Conference

November 8, 2006

Introduction/Background

• EPA is coordinating the fifth national assessment of ambient air toxics data

• Funded through air monitoring grant monies as has been the case in the previous four efforts

• Intended to serve as a vehicle for incorporating the broad spectrum of assessment interests at the federal, state, local and tribal levels

• Designed to:– build on the successes of the four previous efforts;

– continue addressing key and high priority policy relevant questions; and

– ensure broad involvement in the analysis effort through open andfrequent communication of intentions, results and conclusions

Introduction/Background

• Phase I (2001): Analyses and Network Design Recommendations

• Battelle/STI used historical (1990-2000) data

• Phase II (2003): Analyses and Network Design Recommendations

• Battelle/STI used Pilot City (2001-2002) data

• Phase III (2004): Air Toxics Data Analysis Workbook

• STI used historical and Pilot City data (1990-2002)

• Phase IV (2005): Temporal and Spatial Variability papers

• STI used historical and Pilot City data as well as available NATTS (1990-2003)

Introduction/Background• National assessment of ambient air toxics measurements to

be conducted Fall 2006 through Summer 2007

• Effort divided into two parts– The first focuses on enhancing modeling and other assessment

tools• NATA02 - as part of the Risk and Technology Review Rule (RTR)

• Also supporting new modeling platform (CMAQ) development

• Work underway, began in September

– The second will focus on more traditional air quality analyses• Exercising ambient monitoring data to characterize air toxics as well

as perform trends and accountability analyses.

• Scheduled to begin in January 2007

Part I: Enhancing modeling and other

assessment tools

This work addresses one of the primary monitoring objectives

of the air toxics monitoring program:

Air Quality Modeling Evaluation -- Provide data to support

and evaluate dispersion and deposition models

Source: “National Monitoring Strategy Air Toxics Component”, U.S. EPA, 2004


assessment tools

• Estimates for CMAQ boundary conditions– Examine utility of ambient measurements from domestic rural sites;

– Incorporate ambient measurements at remote locations from NOAA’s Climate Modeling and Diagnostics Laboratory*; and

– Supplement with data from literature

*Significant assistance re data provision and interpretation from Steve Montzka, NOAA CMDL

Global Monitoring Division

00YesNaphthalene

11YesEthylene Oxide

13YesAcrylonitrile

02YesAcrolein

00Yes1,3-Dichloropropene(Total)

27Yes1,1,2,2-Tetrachloroethane

some samples18YesYesYes*Trichloroethylene

18YesYesYesTetrachloroethylene

88YesYesFormaldehyde

28YesYesYesDichloromethane

1011YesYesYesBenzene

NoQuinoline

18YesVinyl Chloride

Literature dated17YesYes*Ethylene Dichloride

07YesEthylene Dibromide

28Yes1,2-Dichloropropane

29Yes1,3-Butadiene

18YesYesYesChloroform

58YesYesYesCarbon Tetrachloride

88YesYesAcetaldehyde

Notes

# sites outside CBSA

& 25%+ obs above

MDL

# sites

outside

CBSA AvailableLiteratureCMDL NAME

Domestic ambient data (2001-2003)


assessment tools

• Background concentrations for NATA02– Review/refine the methodology developed and executed for

NATA99 to estimate “background” concentrations

– For NATA, background estimates are concentrations reflecting natural sources, nearby sources (farther than 50km), and unidentified sources

• Model evaluation for NATA02– Investigate specific instances in which NATA99 results diverge

from available monitoring data, where not already understood.

• Identify probable and possible reasons, and recommend better NATA methods, and better monitoring approaches that may allow more insight through future model-to-monitor comparisons.

– Conduct assessment of NATA02 model results.

• Review/refine as necessary the model-to-monitor techniques used in NATA99 to evaluate results of ambient air quality simulations.


assessment tools

• Other modeling platforms (e.g., 1-atmosphere CMAQ)– Evaluate new air toxics modeling platform results (e.g., CMAQ

HAP results)

– Historic ambient data already provided for inclusion in ORD/NOAA Atmospheric Model Evaluation Tool (AMET)


assessment tools• Other related tasks:

– Database development

• Update analysis dataset through 2005

– NATTS

– UATMP and other programs measuring toxics (e.g., STN for particles, PAMS)

– non-HAP species (e.g., O3, PM2.5, CO)

– Legacy air toxics archive (ATA)

– Investigate and apply range of available statistical treatments of values

below detection levels and compare to standard substitution methods.

– Develop approach to and guidance for estimating uncertainties of air toxics concentrations important for application of source apportionment techniques

Part II: Characterization & Accountability

This work addresses primary and secondary objectives

of the air toxics monitoring program:

Trends and Program Accountability – Establish trends and evaluate the effectiveness of HAP reduction strategies

Problem Identification -- Characterize ambient concentrations (and deposition) in local areas

Source: “National Monitoring Strategy Air Toxics Component”, U.S. EPA, 2004


• Characterization – Update the earlier assessments of the magnitude of the air toxics

issue and its spatial variation

• Take advantage of new sites and more recent data

• Characterize spatial variability for pollutants not yet assessed

• Supplement previously used techniques to assess spatial variability (e.g., coefficient of variation) with additional approaches

• Employ site level metadata to understand spatial differences


• Characterization (continued)

– Identify ‘compounds of potential concern’ at the site level using

risk based approach

• Using methods and toxicity values from EPA’s “Air Toxics Risk

Assessment Reference Library, Volumes I-III” 2004, 2004, 2006

• Patterned after “Detroit Air Toxics Initiative - Risk Assessment

Report”, November 2005, State of Michigan Department of

Environmental Quality

• Derive potential risk estimates for cancer and noncancer effects

(inhalation only) based on ambient monitoring data at the site level.

• Focus on 22 NATTS areas but incorporate data from other nearby

sites

Illustrative Example from Detroit Air Toxics Initiative Risk

Assessment Report, Michigan DEQ, November 2005


• Characterization (continued)

– Assess spatial difference in ‘pollutants of potential concern’, and

their relative contribution to the site-level estimate of potential risk

– Evaluate factors influencing variation between sites:

• Suite of pollutants measured

• Sampling and analysis methods

• Detection limits and associated data reporting conventions (e.g.,

treatment of data below the MDL)

• Site-level metadata including monitoring scale, siting, and objectives

• Emissions and proximity of sources

– Compare to model results


• Characterization (continued) – What will we learn/gain from these characterization efforts:

• Severity/magnitude of air toxics issues including the identification of ‘hot spots’;

• Pollutants’ relative contribution to problem;

• The degree to which severity/magnitude, and pollutants contributing to risk vary spatially;

• Insights into how to best examine the spatial character of HAPs relative to those of CAPs (ozone and particles);

• Identified opportunities for improvement in monitoring program (e.g., siting, pollutants, detection limits)

• Basis for collaboration at federal, state and local levels


• Trends/accountability

– Estimate site-level trends

• 18 core HAPs plus – Any additional species identified as contributing substantially to

an area’s overall risk burden; and

– Include comparisons to nearby ozone and particle monitors

• Assess diurnal and seasonal patterns as well as annual trends

• Inter-annual assessments of varying time periods but focus on recent six year period

• Evaluate spatial patterns in inter-annual changes in HAP levels within and across urban areas, and rural versus urban areas

• Expand and refine the methodologies used previously in earlier phases of air toxics data analysis


• Trends/accountability (continued)

– Interpreting the temporal trends & evaluating program

effectiveness

• Use case studies of trends in pre-control ‘hot spots’ to provide

anecdotal evidence of control program results.

• Compare ambient concentration and emissions trends (mass and

toxicity-weighted emissions) to provide context for changes in HAP

levels.

• Analyze patterns in ambient trends for significant decreases in

concentrations and attempt to connect to controls

• Compile/leverage control program database for systematic

comparison with ambient trend data

• Continue to explore the meteorological adjustment for specific air

toxics


• Trends/accountability (continued)– Using insights gained from the above analyses, make recommendations

regarding the formulation and application of program performance

measures based on ambient air toxics data.


• Develop guidance for assessing and analyzing ambient air

quality data for HAPs

– Manual/workbook

• Data access (mechanisms for retrieving data from AQS and supplementing these data);

• Data validation (screening criteria, approaches, treatment of data below MDL);

• Data analysis, visualization and interpretation (characterization, trends and spatial variability analyses), and eventually more advanced analytic topics (source apportionment, meteorological adjustment, model-to-monitor comparisons, etc.)

– Training based on data analysis guidance manual to be offered atdata analysis workshops beginning 2007

Collaboration

• Data set with documentation will be made

available upon completion of analyses

• All analysis plans, work plans, and results

to be posted on the web

• Data analysis workshop tentatively planned

for late Summer/early Fall 2007

• Other ideas/suggestions?

THANK YOU FOR YOUR ATTENTION

James Hemby

Air Quality Analysis Group

Office of Air Quality Standards and Planning

U.S. EPA

919.541.5459

[email protected]

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